This invention relates in general to methods and apparatus used to bill for calls made through a private branch exchange and in particular to methods and apparatus for verifying the identity of the originating station.
Private branch exchanges, or PBX's, such as the types installed in hotels, factories and/or large offices have been known for some time in the prior art. Billing systems utilized to allocate the cost of such systems on a per station/per call basis have typically utilized an accounting service supplied by the serving utility telephone company (e.g. Hotel Billing Information Center "HOBIC" or "QZ" auto-quote) and electromechanical or electronic local call message registers which receive message charging pulses transmitted remotely from the local central office.
From the standpoint of reliability such systems do not perform satisfactorily. The "HOBIC" operator is told by the person placing the call which station he is utilizing. This information received is not verifiable and therefore subject to inconsistencies.
On Dec. 28, 1980, the Federal Communications Commission published Report and Order 80.54 which among other things allows for the resale of interstate long distance telephone service (MTS) by hotel owners to their guests. Guest calls may now be placed via Direct Distance Dialing (DDD) or Wide Area Telephone Service (WATS). The problem raised by this approach is one of accountability and exactly how to bill the cost of such phone calls on a per station basis without utilizing a local full time operator at the private branch exchange location or installing expensive monitoring equipment at each local station. While the cost of long distance phone calls may be routinely calculated by means of a number called, time of day and duration algorithm, the means of verifying the origination station from a plurality of local stations has remained a problem.